Problem: Luis ate 2 slices of pizza. Jessica ate 4 slices. If Luis ate $\dfrac{2}{10}$ of the pizza, what fraction of the pizza was eaten?
Explanation: If 2 slices represent $\dfrac{2}{10}$ of the pizza, there must have been a total of 10 slices. $\text{fraction of pizza eaten} = \dfrac{\text{number of slices eaten}}{\text{number of slices total}}$ They ate ${6}$ out of $10$ slices. They ate $\dfrac{6}{10}$ of the pizza.